Battery temperature control system

ABSTRACT

A battery temperature control system, in temperature rise control, sets a maximum chargeable current and a maximum dischargeable current based on detection values of current, voltage, and temperature of a high-voltage battery, and controls charging/discharging power so that the current of the high-voltage battery does not exceed the maximum chargeable current or the maximum dischargeable current. For this reason, it is possible to prevent the high-voltage battery from abnormal heating and promptly raise its temperature according to change in the internal state of the high-voltage battery. In this control, a plurality of electrical equipment is selectively used. The amplitude of charging/discharging is controlled to reduce vibration noise and driving force fluctuation.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Division of application Ser. No. 12/572,771, filedOct. 2, 2009, which is in turn based on and claims priority to JapanesePatent Applications No. 2008-258345 filed on Oct. 3, 2008, No.2008-259276 filed on Oct. 6, 2008, and No. 2008-262623 filed on Oct. 9,2008, the entire contents of each of which are hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention relates to a battery temperature control systemthat carries out the temperature rise control to raise the temperatureof a battery mounted on a vehicle by its charging/discharging.

BACKGROUND OF THE INVENTION

In general, a battery (secondary battery) is reduced in its internalactivation level at low temperature than at normal temperature and itsinternal resistance is increased. For this reason, even though thecurrent is identical when the battery is discharged, the voltage betweenboth ends is significantly reduced by the internal resistance. Batteryperformance is limited by the voltage between both ends. Therefore, thecontinuously dischargeable duration is shortened with reduction in thebattery temperature and the amount of power that can be supplied fromthe battery is reduced. As for charging, the voltage between both endsis more steeply raised with reduction in the battery temperature and thecontinuously chargeable duration is shortened.

To cope with this, in recent years, to forcibly raise the temperature ofa battery when the battery is at low temperature to promptly ensure itscharge/discharge performance, charging/discharging of the battery isforcibly carried out to accelerate the production of Joule heat withinthe battery and the temperature of the battery is thereby internallyraised.

In JP2001-314039A (US2002/003417), for example, battery temperature isdetected by a temperature sensor and a remaining capacity control centervalue (SOC target value) of the battery is set according to this batterytemperature. When the battery temperature is low, the remaining capacitycontrol center value is shifted to the upper side of a remainingcapacity control range. Then charging/discharging of the battery iscontrolled based on the deviation between this remaining capacitycontrol center value and the actual remaining capacity (SOC). Theproduction of Joule heat within the battery is thereby accelerated toraise the temperature of the battery.

As the charging/discharging current of a battery is increased, its Jouleheating is increased and its temperature can be more quickly raised. Inthe above technique, however, charging/discharging power is controlledaccording to the temperature and remaining capacity of a battery.Therefore, when the internal state of the battery (for example, theinternal resistance, the state of internal polarization, and the like)changes, it is likely that the charging/discharging power of the batterymay go out of an appropriate range. In the temperature rise control, asa result, the charging/discharging power of the battery is excessivelylimited and this results in delayed temperature rise in the battery.Conversely, it is also likely that excessive charging/discharging poweris passed and the battery abnormally produces heat and this leads todeterioration or breakage of the battery.

In JP 2007-28702A and JP 2007-12568A, the production of Joule heatwithin a battery is accelerated to raise the temperature of the batteryby repeating charging and discharging of the battery alternately andperiodically when the battery temperature detected by a temperaturesensor is low.

When either charging or discharging of a battery is only continuouslycarried out for a long time, the polarizing effect of the battery isincreased and significant voltage change occurs. As a countermeasuretherefor, it is effective to alternately and periodically repeatcharging and discharging during the execution of the temperature risecontrol. However, the cycle of switching between charging anddischarging and the current amplitude (power amplitude) for achievingoptimum temperature rise vary depending on the internal state of thebattery that varies from hour to hour. Such internal state of a batteryincludes not only remaining capacity and battery temperature but alsointernal resistance, production tolerance, deterioration, and the like.Therefore, it is preferable to vary the cycle period and the amplitudeaccording to the internal state of a high-voltage battery with respectto the cycle period and amplitude of charging/discharging for bringingout the maximum temperature rise performance. However, the cycle periodor amplitude of charging/discharging for achieving optimum temperaturerise may be difficult to implement depending on the type of electricalequipment used for the temperature rise control. For example, when thecycle period of charging/discharging is too short to meet theperformance limit of the electrical equipment or the amplitude is toolarge to meet the performance limit of the electrical equipment, thefollowing takes place: the current of the electrical equipment exceedsan allowable current; therefore, there is a possibility that the optimumcycle period or amplitude cannot be achieved. As a result, theperformance of the temperature rise control is degraded and temperaturerise in the battery is decelerated.

Further, when a boost converter is used to repeat periodicalcharging/discharging, the following takes place: input/output current toa capacitor of the boost converter is produced and vibration noise isproduced in the capacitor. In JP 2008-78167A (US 2008/0068775), acushioning material layer for absorbing vibration is added to theinterior of a capacitor to reduce this vibration noise. In JP2008-66503A, the electrode plane of a capacitor is formed of resinmaterial low in coefficient of elasticity by molding.

In JP 2008-162397A, in a hybrid vehicle in which the driving force of amotor is transmitted through a gear box, when gear rattle in a gear iscaused by fluctuation in the driving force of the motor, engine outputcorrection or the like is carried out.

According to these conventional technologies, however, the followingoccurrence is expected depending on the cycle period or amplitude ofbattery charging/discharging in the temperature rise control: the effectof reducing noise such as vibration noise may be insufficient or theeffect of reducing fluctuation in driving force may be insufficient.

SUMMARY OF THE INVENTION

It is a first object of the invention to prevent a battery from abnormalheating in the temperature rise control even when the internal state ofthe battery changes and to promptly raise the temperature of thebattery.

It is a second object of the invention to enhance the performance of thetemperature rise control by selection from among multiple pieces ofelectrical equipment capable of operating charging/discharging of abattery.

It is a third object of the invention to effectively reduce noise suchas vibration noise and fluctuation in driving force that may occurduring the execution of the temperature rise control.

To achieve the first object, in a temperature control system for abattery of the invention, a maximum chargeable current and a maximumdischargeable current are set based on the current, voltage, andtemperature of a battery; and charging/discharging power is controlledto raise the temperature of the battery so that the current of thebattery does not exceed the maximum chargeable current or the maximumdischargeable current. When the above the temperature rise control iscarried out, based on the maximum chargeable current and the maximumdischargeable current, the switching period and/or amplitude ofcharging/discharging in the temperature rise control is set.

To achieve the second object, in a temperature control system for abattery of the invention, when the above the temperature rise control iscarried out, based on at least one of the cycle period and amplitude ofcharging and/or discharging of a battery, electrical equipment thatoperates the charging and/or discharging of the battery is selected fromamong multiple pieces of electrical equipment.

To achieve the third object, in a temperature control system for abattery of the invention, during the execution of the temperature risecontrol, at least either the cycle period or amplitude of chargingand/or discharging of a battery is limited so that vibration noiseand/or driving force fluctuation is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription made with reference to the accompanying drawings. In thedrawings:

FIG. 1 is a schematic diagram illustrating the system of an electricvehicle in a first embodiment of the invention;

FIG. 2 is a flowchart illustrating the processing in a the temperaturerise control routine in the first embodiment;

FIG. 3 is a graph indicating the relation between the temperature andinternal resistance of a high-voltage battery;

FIG. 4 is a flowchart illustrating the processing in a the temperaturerise control routine in a second embodiment;

FIG. 5 is a graph indicating a use range with respect to the current andvoltage of a high-voltage battery;

FIG. 6 is a flowchart illustrating the processing in a the temperaturerise control routine in a third embodiment;

FIG. 7 is a graph illustrating an example of map data for calculatingthe internal resistance of a high-voltage battery using its detectedtemperature as a parameter;

FIG. 8 is a flowchart illustrating the processing in a the temperaturerise control routine in a fourth embodiment;

FIG. 9 is a flowchart illustrating the processing in a the temperaturerise control routine in a fifth embodiment;

FIG. 10 is a flowchart illustrating the processing in a the temperaturerise control routine in a sixth embodiment;

FIG. 11 is a flowchart illustrating the processing in a the temperaturerise control routine in a seventh embodiment;

FIG. 12 is a flowchart illustrating the processing in a the temperaturerise control routine in an eighth embodiment;

FIG. 13 is a flowchart illustrating the processing in a the temperaturerise control routine in a ninth embodiment;

FIG. 14 is a graph illustrating an example of electrical equipmentselection map data for the temperature rise control in the ninthembodiment;

FIG. 15 is a flowchart illustrating the processing in a the temperaturerise control routine in a tenth embodiment;

FIG. 16A is a graph illustrating an example of selection map data for aDC-DC converter in a normal case;

FIG. 16B is a graph illustrating an example of selection map data forthe DC-DC converter in an abnormal case;

FIG. 17 is a flowchart illustrating a the temperature rise controlroutine in an eleventh embodiment;

FIG. 18 is a graph conceptually illustrating an example of a map forcalculating an amplitude limit value of charging/discharging currentbased on the cycle of charging/discharging in the eleventh embodiment;

FIG. 19 is a flowchart illustrating a the temperature rise controlroutine in a twelfth embodiment;

FIG. 20 is a graph illustrating an example of map data for calculatingan amplitude limit value of charging/discharging current based on thecycle of charging/discharging and vehicle speed in the twelfthembodiment;

FIG. 21 is a flowchart illustrating a the temperature rise controlroutine in a thirteenth embodiment; and

FIG. 22 is a graph illustrating an example of map data for calculatingan amplitude limit value of charging/discharging current based on thecycle of charging/discharging and an accelerator pedal depression amountin the thirteenth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereafter, the present invention will be described with reference tomultiple embodiments, which are applied to an electric vehicle.

First Embodiment

As illustrated in FIG. 1, an electric vehicle is mounted with: a motor11 as a vehicle driving source; a high-voltage battery 12 as a powersource for this motor 11; and a low-voltage battery 17 as a power sourcefor various pieces of electrical equipment (electrical loads). The motor11 is comprised of a synchronous generator motor as a motor also used asa generator. The high-voltage battery 12 is comprised of a secondarybattery, such as a lithium (Li)-ion battery and a nickel-hydrogenbattery, that outputs high voltage of, for example, 200 to 300V.

Between the motor 11 and the high-voltage battery 12, a boost converter13 and an inverter 14 are provided. When the motor 11 is driven, a DCvoltage outputted from the high-voltage battery 12 is stepped up at theboost converter 13 and converted into an AC voltage at the inverter 14and then supplied to the motor 11. As a result, the motor 11 is rotatedand the driving wheels 15 of the vehicle are driven. When the motor 11generates power, the motor 11 is rotated by the torque of the drivingwheels 15 and AC power is generated. Then this AC power is convertedinto DC power at the inverter 14 and stepped down at the boost converter13 and the high-voltage battery 12 is charged therewith.

The low-voltage battery 17 is comprised of a secondary battery, such asa lead storage battery, that outputs DC voltage (for example, 12V) lowerthan the output voltage of the high-voltage battery 12. The low-voltagebattery 17 is connected to the power supply line of the high-voltagebattery 12 through a two-way DC-DC converter 18. When the low-voltagebattery 17 is charged, the output voltage of the high-voltage battery 12is stepped down at the two-way DC-DC converter 18 and the low-voltagebattery 17 is charged therewith.

Meanwhile, a smoothing capacitor (not shown) of the boost converter 13is precharged by stepping up the output voltage of the low-voltagebattery 17 at the two-way DC-DC converter 18 and supplying it to thepower supply line of the high-voltage battery 12 immediately after anignition switch (not shown) is turned on. Alternatively, the temperatureof the high-voltage battery 12 may be raised by carrying out chargingand/or discharging of the high-voltage battery 12 by the step-up/downoperation of the two-way DC-DC converter 18 between the high-voltagebattery 12 and the low-voltage battery 17 during the execution of thetemperature rise control described late.

The operation of the boost converter 13, inverter 14, and two-way DC-DCconverter 18 is controlled by ECU (electronic control unit) 20. This ECU20 is comprised of a microcomputer including a CPU 21 and includes, inaddition to the CPU 21, ROM 22 for storing various programs and data,such as initial values, RAM 23 for temporarily storing varied data, andthe like.

This ECU 20 is inputted with signals required for managingcharging/discharging of the high-voltage battery 12. Examples of suchsignals include signals indicating: the charging/discharging current ofthe high-voltage battery 12 detected by a current sensor 24 (currentdetecting means); the voltage of the high-voltage battery 12 detected bya voltage sensor 25 (voltage detecting means); the temperature of thehigh-voltage battery 12 detected by a temperature sensor 26 (temperaturedetecting means); and the like. In addition, the following signals areinputted to the ECU 20: a shift position signal from a shift positionsensor 28 for detecting the operating position of a shift lever 27; anaccelerator position signal from an accelerator position sensor 30 fordetecting the depression amount of an accelerator pedal 29; a brakepedal position signal from a brake pedal position sensor 32 fordetecting the depression amount of a brake pedal 31; a vehicle speedsignal from a vehicle speed sensor 33; a rotation angle signal from arotation angle sensor 34 for detecting the rotation angle of the motor11; and the like.

In the first embodiment configured as described above, the ECU 20calculates a request torque based on the accelerator position signalfrom the accelerator position sensor 30, the vehicle speed signal fromthe vehicle speed sensor 33, and the like. Then it controls theoperation of the motor 11 so that this request torque is provided.

Further, the ECU 20 executes the temperature rise control routine ofFIG. 2, described below, and thereby carries out the temperature risecontrol when the temperature of the high-voltage battery 12 detected bythe temperature sensor 26 is lower than a predetermined temperature. Inthis the temperature rise control, the temperature of the high-voltagebattery 12 is raised by internal heating due to itscharging/discharging. It is known that the Joule heat produced withinthe high-voltage battery 12 during the execution of this the temperaturerise control is in proportion to the square of current. Therefore,temperature rise in the high-voltage battery 12 can be accelerated bypassing larger current through the high-voltage battery 12 regardless ofthe direction of current passage (whether charge or discharge).

In the first embodiment, consequently, the following procedure is taken:the current, voltage, and temperature of the high-voltage battery 12 aresampled at predetermined time intervals to detect the present current,voltage, and temperature; and these three detection values are used tocalculate the maximum dischargeable current Ibmax and the maximumchargeable current Ibmin that can be achieved under the batteryconditions at the sampling time. Then the maximum dischargeable currentIbmax and the maximum chargeable current Ibmin are compared with eachother and charging or discharging of the high-voltage battery 12 isdetermined so that a larger current can be passed. Thus the temperaturerise control corresponding to the internal state of the high-voltagebattery 12 can be implemented.

The present currents and voltages sampled at the predetermined timeintervals are determined by the battery characteristics including eventhe influence of the polarized state, variation, age deterioration, andthe like of the high-voltage battery 12. Therefore, the maximumchargeable/dischargeable current determined based on the present currentand voltage determines the performance of the high-voltage battery 12according to the state of the battery at the time when they weresampled. This makes it possible to accurately estimate the marginalperformance of the high-voltage battery 12 even when the state of thehigh-voltage battery 12 changes. As a result, it is possible to preventdeterioration and breakage of the high-voltage battery 12 and to quicklyraise the temperature of the high-voltage battery 12.

At the next sampling time, the actual current and voltage are detectedagain. Therefore, even though the state of the battery changes during aperiod between one sampling time and another, the degree of itsinfluence can be corrected. That is, theoretically, the shorter asampling cycle, the better the charging/discharging performance of thehigh-voltage battery 12 can be exerted even though the state of thebattery suddenly changes.

In the first embodiment, the temperature rise control in thehigh-voltage battery 12 is carried out by the ECU 20 in accordance withthe temperature rise control routine in FIG. 2 as described below. Thetemperature rise control routine in FIG. 2 is repeatedly carried out atpredetermined time intervals during the on-period of the ignition switch(not shown).

When this routine is started, first, the following data is retrieved atstep 101: the current (detected current) Ip of the high-voltage battery12 detected by the current sensor 24; the voltage (detected voltage) Vpof the high-voltage battery 12 detected by the voltage sensor 25; andthe temperature (detected temperature) Tp of the high-voltage battery 12detected by the temperature sensor 26.

At step 102, thereafter, it is checked whether the temperature of thehigh-voltage battery 12 is within a the temperature rise control rangebased on whether the detected temperature Tp is lower than apredetermined temperature Tth. When the detected temperature Tp is equalto or higher than the predetermined temperature Tth, it is determinedthat the temperature rise control need not be carried out. Then thefollowing processing is not carried out and this routine is terminated.

When it is determined at step 102 that the detected temperature Tp islower than the predetermined temperature Tth, the processing of step 103and the following steps in the temperature rise control is carried outas described below. At step 103, first, the maximum dischargeablecurrent Ibmax and maximum chargeable current Ibmin are set using mapdata, a mathematical expression, or the like based on the detectedcurrent Ip, detected voltage Vp, and detected temperature Tp. The map ormathematical expression used in this processing can be set bydetermining the relation between the current, voltage, temperature ofthe high-voltage battery 12 and the maximum chargeable/dischargeablecurrent (Ibmin, Ibmax) based on experimental data, design data,simulation, or the like and storing it as a map or a mathematicalexpression. In the first embodiment, charging current is expressed as anegative value and discharging current is expressed as a positive value.Step 103 functions as a maximum chargeable/dischargeable current settingmeans.

At step 104, thereafter, the absolute value of the maximum dischargeablecurrent Ibmax and the absolute value of the maximum chargeable currentIbmin are compared with each other. When the absolute value of themaximum dischargeable current Ibmax is larger, the following processingis carried out at step 105: based on the maximum dischargeable currentIbmax and the detected temperature Tp, a command power Pb that attainsmaximum discharge is calculated by map data Map1. This map data Map1 canbe set by determining the relation among the maximum dischargeablecurrent Ibmax, the detected temperature Tp, and the command power Pb byexperimental data, design data, simulation result, or the like andstoring it as a map.

Meanwhile, when it is determined at step 104 that the absolute value ofthe maximum dischargeable current Ibmax is smaller than the absolutevalue of the maximum chargeable current Ibmin, the following processingis carried out at step 106: based on the maximum chargeable currentIbmin and the detected temperature Tp, a command power Pb that attainsmaximum charge is calculated by map data Map2. This map data Map2 canalso be set beforehand based on experimental data, design data,simulation result, or the like.

At step 107, thereafter, an actuator (for example, the boost converter13, inverter 14, motor 11, two-way DC-DC converter 18, or the like) iscontrolled according to the command power Pb set at step 105 or 106.Then the charging/discharging power of the high-voltage battery 12 iscontrolled so that it agrees with the command power Pb. Thecharging/discharging power is thereby controlled so that the current ofthe high-voltage battery 12 does not exceed the maximum chargeablecurrent Ibmin or the maximum dischargeable current Ibmax and thetemperature of the high-voltage battery 12 is raised by its internalheating. Steps 104 to 107 function as a the temperature rise controllingmeans.

According to the first embodiment, the following can be implemented inthe temperature rise control: based on the current, voltage, andtemperature of the high-voltage battery 12, the maximum chargeablecurrent Ibmin and the maximum dischargeable current Ibmax are set; andthe charging/discharging power is controlled so that the current of thehigh-voltage battery 12 does not exceed the maximum chargeable currentIbmin or the maximum dischargeable current Ibmax. When the internalstate of the high-voltage battery 12 changes, it is possible to vary themaximum chargeable current Ibmin and the maximum dischargeable currentIbmax according to this change in the internal state of the high-voltagebattery 12 and control the charging/discharging power. Even when theinternal state of the high-voltage battery 12 changes, thecharging/discharging power of the high-voltage battery 12 can becontrolled to be within an appropriate range of the temperature risecontrol. As described above, it is possible to prevent the high-voltagebattery 12 from abnormal heating and further promptly raise thetemperature of the high-voltage battery 12.

Second Embodiment

In the first embodiment, the maximum chargeable current Ibmin and themaximum dischargeable current Ibmax in the temperature rise control areset by a map, a mathematical expression, or the like based on thecurrent, voltage, and temperature of the high-voltage battery 12. Asindicated in FIG. 3, however, the internal resistance of thehigh-voltage battery 12 is increased under cold condition. Therefore, itis preferable that the maximum chargeable current Ibmin and the maximumdischargeable current Ibmax in the temperature rise control should bedetermined based on use limitation on voltage in the high-voltagebattery 12.

In the second embodiment illustrated in FIG. 4 and FIG. 5, consequently,to accurately set the maximum chargeable current Ibmin and the maximumdischargeable current Ibmax, the difference between the upper and lowerlimit values within the voltage use range (allowable range) of thehigh-voltage battery 12 illustrated in FIG. 5 and the sampled presentvoltage is determined, allowable voltage rise and drop to the upper andlower limit values within the voltage use range are calculated, and themaximum chargeable current Ibmin and the maximum dischargeable currentIbmax are set using the allowable voltage rise and drop, batterytemperature that has influence on the internal resistance, and the upperand lower limit values within the current use range of the high-voltagebattery 12.

When this routine is started in the second embodiment, the processing iscarried out as described below. At step 201, first, the detected currentIp, detected voltage Vp, and detected temperature Tp detected by therespective sensors 24, 25, 26 are retrieved. At step 202, thereafter, itis checked whether the detected temperature Tp is lower than thepredetermined temperature Tth. When the detected temperature Tp is equalto or higher than the predetermined temperature Tth, it is determinedthat the temperature rise control need not be carried out. Then thefollowing processing is not carried out and this routine is terminated.

When it is determined at step 202 that the detected temperature Tp islower than the predetermined temperature Tth, the processing of step 203and the following steps in the temperature rise control is carried outas described below. At step 203, first, an upper limit current Ibmax.bsand low limit current Ibmin.bs within the current use range (Refer toFIG. 5) determined by the state of the battery are set. At the sametime, an upper limit voltage Vbmax and a lower limit voltage Vbminwithin the voltage use range (FIG. 5) determined by the characteristicsof the battery are set. The current use range and the voltage use rangecan be set beforehand based on experimental data, design data,simulation result, or the like. Step 203 functions as a use rangesetting means.

At step 204, thereafter, the following processing is carried out: basedon the upper and lower limit voltages (Vbmax, Vbmin) within the voltageuse range and the present detected voltage Vp, an allowable voltage riseΔVbmax and an allowable voltage drop ΔVbmin that are differences betweenthem are calculated.Allowable voltage rise: ΔVbmax=Vbmax−VpAllowable voltage drop: ΔVbmin=Vbmin−Vp

At step 205, thereafter, a dischargeable current Ibmax.vbmin and achargeable current Ibmin.vbmax are calculated by maps (Map3, Map4) basedon the allowable voltage rise and drop (ΔVbmax, ΔVbmin) and the detectedtemperature Tp.

[Dischargeable Current Ibmax.vbmin Determined from Allowable VoltageDrop ΔVbmin]Ibmax.vbmin=Map3(ΔVbmin,Tp)

[Chargeable Current Ibmin.vbmax Determined from Allowable Voltage RiseΔVbmax]Ibmin.vbmax=Map4(ΔVbmax,Tp)

These maps (Map3, Map4) can also be set beforehand based on experimentaldata, design data, simulation result, or the like.

At step 206, thereafter, the upper limit current Ibmax.bs within thecurrent use range and the dischargeable current Ibmax.vbmin are comparedwith each other. Then the lower one is selected as the maximumdischargeable current Ibmax. The lower limit current Ibmin.bs within thecurrent use range and the chargeable current Ibmin.vbmax are comparedwith each other. Then the one lower in absolute value is selected as themaximum chargeable current Ibmin.Maximum dischargeable current: Ibmax=Min(Ibmax.bs,Ibmax.vbmin)Maximum chargeable current: Ibmin=Max(Ibmin.bs,Ibmin.vbmax)

The discharging current takes a positive value and the charging currenttakes a negative value. Thus the maximum dischargeable current Ibmax andthe maximum chargeable current Ibmin are set so that they do not exceedthe current use range.

At step 207, thereafter, the absolute value of the maximum dischargeablecurrent Ibmax and the absolute value of the maximum chargeable currentIbmin are compared with each other. When the absolute value of themaximum dischargeable current Ibmax is larger, the following processingis carried out at step 208: based on the maximum dischargeable currentIbmax and the detected temperature Tp, the command power Pb that attainsmaximum discharge is calculated by the map data Map1. Meanwhile, when itis determined at step 207 that the absolute value of the maximumdischargeable current Ibmax is smaller than the absolute value of themaximum chargeable current Ibmin, the following processing is carriedout at step 209: based on the maximum chargeable current Ibmin and thedetected temperature Tp, the command power Pb that attains maximumcharge is calculated by the map data Map2.

At step 210, thereafter, the actuator (the boost converter 13, inverter14, motor 11, two-way DC-DC converter 18, or the like) is controlledaccording to the command power Pb set at step 208 or 209. Then thecharging/discharging power of the high-voltage battery 12 is controlledso that the command power Pb is attained. The charging/discharging poweris thereby controlled so that the current of the high-voltage battery 12does not exceed the maximum chargeable current Ibmin or the maximumdischargeable current Ibmax and the temperature of the high-voltagebattery 12 is raised.

In the second embodiment, the following processing is carried out: thedifferences between the upper and lower limit values within the voltageuse range of the high-voltage battery 12 and the sampled present voltageis determined; allowable voltage rise and drop to the upper and lowerlimit values within the voltage use range are calculated from thesedifferences; and the maximum chargeable current Ibmin and the maximumdischargeable current Ibmax are set using the above allowable voltagerise and drop, the temperature of the high-voltage battery 12 that hasinfluence on its internal resistance, and the upper and lower limitvalues within the current use range of the high-voltage battery 12. Thismakes it possible to take the internal state of the high-voltage battery12 into account in the temperature rise control and limit thecharging/discharging power so that neither the current nor voltage ofthe high-voltage battery 12 exceeds the respective use range. Even whenvoltage changes, it is possible to efficiently accelerate temperaturerise by the charging/discharging of the high-voltage battery 12 andprevent the high-voltage battery 12 from abnormal heating due toexcessive charging/discharging current.

Third Embodiment

In the second embodiment, to take into account the influence of theinternal resistance of the high-voltage battery 12, the detectedtemperature Tp of the high-voltage battery 12 is used to set the maximumchargeable current Ibmin and the maximum dischargeable current Ibmax. Inthe third embodiment illustrated in FIG. 6 and FIG. 7, attention isdirected to the relation that under cold condition, the internalresistance of the high-voltage battery 12 is increased with reduction inits temperature. Then the internal resistance Rb is estimated based onthe detected temperature Tp of the high-voltage battery 12 and theestimated internal resistance Rb is used to set the maximum chargeablecurrent Ibmin and the maximum dischargeable current Ibmax.

In the temperature rise control routine in the third embodimentillustrated in FIG. 6, the processing of step 205 in the temperaturerise control routine in FIG. 4 is replaced with the processing of steps205 a and 205 b. The processing of the other steps is the same as in theroutine in FIG. 4.

In this routine, the allowable voltage rise ΔVbmax and the allowablevoltage drop ΔVbmin are calculated from the differences between theupper and lower limit voltages (Vbmax, Vbmin) within the voltage userange and the present detected voltage Vp at step 204. At step 205 a,thereafter, the internal resistance Rb corresponding to the presentdetected temperature Tp is calculated with reference to map data Map5 inFIG. 7. This map data is used to calculate the internal resistance Rb ofthe high-voltage battery 12 using its detected temperature Tp as aparameter.Rb=Map5(Tp)

This map data Map5 may be set beforehand based on experimental data,design data, simulation result, or the like so that the internalresistance Rb is increased with reduction in the detected temperatureTp.

At step 205 b, thereafter, the dischargeable current Ibmax.vbmin and thechargeable current Ibmin.vbmax are calculated from map data (Map6, Map7)based on the allowable voltage rise and drop (ΔVbmax, ΔVbmin) and theinternal resistance Rb.

[Dischargeable Current Ibmax.vbmin Determined from Allowable VoltageDrop ΔVbmin]Ibmax.vbmin=Map6(ΔVbmin,Rb)

[Chargeable Current Ibmin.vbmax Determined from Allowable Voltage RiseΔVbmax]Ibmin.vbmax=Map7(ΔVbmax,Rb)

These pieces of map data (Map6, Map7) are also set beforehand based onexperimental data, design data, simulation result, or the like.

Thereafter, the processing of steps 206 to 210 is carried out and themaximum dischargeable current Ibmax and the maximum chargeable currentIbmin are set by the same method as in the second embodiment. Thecommand power Pb that attains maximum charge/discharge is therebycalculated and the actuator is controlled to raise the temperature ofthe high-voltage battery 12.

In the third embodiment, the internal resistance Rb is estimated basedon the detected temperature Tp of the high-voltage battery 12 and theestimated internal resistance Rb is used to set the maximum chargeablecurrent Ibmin and the maximum dischargeable current Ibmax. Even whenchange in the internal resistance of the high-voltage battery 12 occurs,it is possible to accurately set the maximum chargeable current Ibminand the maximum dischargeable current Ibmax and achieve quicktemperature rise in the high-voltage battery 12.

Fourth Embodiment

During the execution of the temperature rise control, a driver maydepress the accelerator pedal 29 to quickly accelerate or the brakepedal 31 to quickly decelerate. When the temperature rise control iscontinued in these cases, it is likely that theacceleration/deceleration performance is degraded and the driver'sacceleration/deceleration request cannot be met.

In the fourth embodiment illustrated in FIG. 8, consequently, the degreeof the driver's acceleration/deceleration request (the driver'sintention to drive) is determined from output signals from theaccelerator position sensor 30 and the brake pedal position sensor 32.When the driver requests quick acceleration or quick deceleration beyonda predetermined range, the temperature rise control is prohibited andthe charging/discharging power of the high-voltage battery 12 iscontrolled so as to meet the driver's acceleration/deceleration request.

In the fourth embodiment, the temperature rise control routine in FIG. 8is repeatedly carried out at predetermined time intervals during theon-period of the ignition switch. The processing of steps 301, 302, and305 to 309 in this routine is the same as the processing of steps 101 to107 in the temperature rise control routine in FIG. 2 described inrelation to the first embodiment. That is, in the temperature risecontrol routine in FIG. 8, processing of two steps, steps 303 and 304,are added between step 102 and step 103 in the temperature rise controlroutine in FIG. 2.

When the temperature rise control routine in FIG. 8 is started, theprocessing is carried out as described below. At step 301, the detectedcurrent Ip, detected voltage Vp, and detected temperature Tp detected bythe respective sensors 24, 25, 26 are retrieved. When it is subsequentlydetermined at step 302 that the detected temperature Tp is lower thanthe predetermined temperature Tth, a required acceleration Aacc and arequired deceleration Abrk requested by the driver are calculated atstep 303 from the output signals from the accelerator position sensor 30and the brake pedal position sensor 32 by a map or the like. Theprocessing of step 303 functions as a driving intention detecting means.

At step 304, thereafter, it is checked whether the required accelerationAacc is lower than a predetermined acceleration Aath and the requireddeceleration Abrk is lower than a predetermined deceleration Abth. Whenthe result of the determination reveals that the required accelerationAacc is equal to or higher than the predetermined acceleration Aath orthe required deceleration Abrk is equal to or higher than thepredetermined deceleration Abth, the following processing is not carriedout. (That is, when the driver requests quick acceleration or quickdeceleration beyond a predetermined range, the following processing isnot carried out.) Then this routine is terminated. As a result, thetemperature rise control is prohibited and the charging/dischargingpower of the high-voltage battery 12 is controlled so that the driver'sacceleration/deceleration request is met.

Meanwhile, when it is determined at step 304 that the requiredacceleration Aacc is lower than the predetermined acceleration Aath andthe required deceleration Abrk is lower than the predetermineddeceleration Abth, it is determined that the temperature rise control ispermitted. Then the processing of step 305 and the following steps iscarried out and command charge/discharge power Pb that attains maximumcharge/discharge in the temperature rise control is set. The commandpower is set by the same processing as that of steps 103 to 107 in thetemperature rise control routine in FIG. 2 described in relation to thefirst embodiment. Then the actuator is controlled according to thiscommand power Pb and the charging/discharging power of the high-voltagebattery 12 is controlled so that the command power Pb is attained.

In the fourth embodiment, degree of a driver's acceleration/decelerationrequest is determined. When the driver requests quick acceleration orquick deceleration beyond a predetermined range, the temperature risecontrol is prohibited. Thus the driver's acceleration/decelerationrequest can be met any time, even during the execution of thetemperature rise control.

Fifth Embodiment

Even though there is a margin between the actual charging/dischargingcurrent and the maximum chargeable/dischargeable current (Ibmin, Ibmax),the high-voltage battery 12 may be overcharged or undercharged dependingon the remaining capacity SOC of the high-voltage battery 12 when thetemperature rise control is continued.

In the fifth embodiment illustrated in FIG. 9, consequently, theremaining capacity SOC of the high-voltage battery 12 is calculated.When the calculated remaining capacity SOC is out of a predeterminednormal use range (SOCmin to SOCmax), power control to the direction inwhich the remaining capacity SOC gets out of the normal use range isprohibited in the temperature rise control.

In the fifth embodiment, the processing of steps 401 to 406 in thetemperature rise control routine in FIG. 9 is the same as the processingof steps 101 to 106 in the temperature rise control routine in FIG. 2described in relation to the first embodiment.

When this routine is started, the processing is carried out as describedbelow. The command charge/discharge power Pb that attains maximumcharge/discharge in the temperature rise control is set by theprocessing of steps 401 to 406. At step 407, thereafter, the remainingcapacity SOC of the high-voltage battery 12 is calculated. Any methodcan be used to calculate the remaining capacity SOC. For example, thecharging/discharging current of the high-voltage battery 12 may beintegrated and this integration value may be used to calculate theremaining capacity SOC. The processing of step 407 functions as aremaining capacity determining means.

At step 408, thereafter, the present remaining capacity SOC is comparedwith the lower limit value SOCmin within the normal use range. When thepresent remaining capacity SOC is lower than the lower limit valueSOCmin within the normal use range, discharging is prohibited at step409 and only charging is permitted. In this case, the following takesplace on a case-by-case basis. When the command power Pb that attainsmaximum discharge in the temperature rise control is charging power(power of a negative value), this command power Pb is used as theultimate command power. When the command power Pb that attains maximumdischarge in the temperature rise control is discharging power (power ofa positive value), the ultimate command power Pb is 0.Pb=Min(0,Pb)

When it is determined at step 408 that the present remaining capacitySOC is equal to or higher than the lower limit value SOCmin within thenormal use range, the processing of step 409 is not carried out.

At step 410, thereafter, the present remaining capacity SOC is comparedwith the upper limit value SOCmax within the normal use range. When thepresent remaining capacity SOC is higher than the upper limit valueSOCmax within the normal use range, charging is prohibited at step 411and only discharging is permitted. In this case, the following takesplace on a case-by-case basis. When the command power Pb that attainsthe maximum discharge in the temperature rise control is dischargingpower (power of a positive value), this command power Pb is used as theultimate command power. When the command power Pb that attains maximumdischarge in the temperature rise control is charging power (power of anegative value), the ultimate command power Pb is 0.Pb=Max(0,Pb)

When it is determined at step 410 that the present remaining capacitySOC is equal to or lower than the upper limit value SOCmax within thenormal use range, the processing of step 411 is not carried out.

At step 412, thereafter, the actuator is controlled according to thecommand power Pb and the charging/discharging power of the high-voltagebattery 12 is controlled so that the command power Pb is attained.

As described above, when the remaining capacity SOC of the high-voltagebattery 12 is out of the normal use range (SOCmin to SOCmax) in thetemperature rise control, the power control to the direction in whichthe remaining capacity SOC gets out of the normal use range isprohibited in the temperature rise control. As a result of theabove-described control, it is possible to prevent the high-voltagebattery 12 from being overcharged or undercharged during the temperaturerise control and the life of the high-voltage battery 12 from beingshortened by the temperature rise control.

In the fifth embodiment, when the remaining capacity SOC of thehigh-voltage battery 12 is out of the normal use range (SOCmin toSOCmax) in the temperature rise control, only the power control to thedirection in which the remaining capacity SOC gets out of the normal userange is prohibited, and the power control to the direction in which theremaining capacity SOC approaches the normal use range is permitted.This makes it possible to recover the remaining capacity SOC during theexecution of the temperature rise control and achieve both thesecurement of the remaining capacity SOC and the execution of thetemperature rise control.

In this embodiment, however, the entire temperature rise control may beprohibited when the remaining capacity SOC of the high-voltage battery12 is out of the normal use range (SOCmin to SOCmax).

Alternatively, when the remaining capacity SOC is higher than the upperlimit value SOCmax within the normal use range in the temperature risecontrol, the temperature rise control may be carried out only bydischarging. When the remaining capacity SOC is lower than the lowerlimit value SOCmin within the normal use range, the temperature risecontrol may be carried out only by charging.

Sixth Embodiment

In each of the above embodiments, only either charging or dischargingmay be continuously carried out during the execution of the temperaturerise control. However, when charging or discharging is only continuouslycarried out for a long time, the polarizing effect of the high-voltagebattery 12 is increased and significant voltage change occurs.

As a countermeasure therefor, charging and discharging may bealternately and periodically repeated during the execution of thetemperature rise control. However, the charging/discharging switchingperiod and the current amplitude (power amplitude) for achieving optimumtemperature rise vary from time to time according to the internal stateof the high-voltage battery 12. Such internal state include not only theremaining capacity SOC and the battery temperature but also the internalresistance, production tolerance, deterioration, and the like. However,it has been conventionally impossible to achieve thecharging/discharging switching period or amplitude for deliveringtemperature raising performance to the maximum when the internal stateof a battery changes.

In the sixth embodiment illustrated in FIG. 10, the temperature risecontrol is carried out by setting the maximum chargeable current Ibminand the maximum dischargeable current Ibmax by the same method as in theabove embodiments. Based on the maximum chargeable current and themaximum dischargeable current, the charging/discharging switching periodand amplitude in the temperature rise control are set.

In the sixth embodiment, the processing is carried out as describedbelow. When the temperature rise control routine in FIG. 10 is started,first, the detected current Ip, detected voltage Vp, and detectedtemperature Tp detected by the respective sensors 24, 25, 26 areretrieved at step 501. At step 502, thereafter, it is checked whetherthe detected temperature Tp is lower than the predetermined temperatureTth. When the detected temperature Tp is equal to or higher than thepredetermined temperature Tth, it is determined that the temperaturerise control need not be carried out. Then the following processing isnot carried out and this routine is terminated.

When it is determined at step 502 that the detected temperature Tp islower than the predetermined temperature Tth, the processing of step 503and the following steps in the temperature rise control is carried outas described below. At step 503, first, the maximum dischargeablecurrent Ibmax and the maximum chargeable current Ibmin are set by a map,a mathematical expression, or the like based on the detected current Ip,detected voltage Vp, and detected temperature Tp. Also in the sixthembodiment, the charging current is expressed as a negative value andthe discharging current is expressed as a positive value.

At step 504, thereafter, the absolute value of the maximum dischargeablecurrent Ibmax and the absolute value of the maximum chargeable currentIbmin are added to provide a charging/discharging amplitude Ibamp.Ibamp=|Ibmax|+|Ibmin|

At step 505, thereafter, a charging/discharging switching period Pswcorresponding to the present charging/discharging amplitude Ibamp anddetected temperature Tp is calculated with reference to map data Map10.This map data is used to calculate the charging/discharging switchingperiod Psw using the charging/discharging amplitude Ibamp and thedetected temperature Tp as parameters. The map data Map10 may be setbeforehand based on experimental data, design data, simulation result,or the like.

At step 506, thereafter, the command power Pb is calculated by thefollowing expression using the charging/discharging amplitude Ibamp,charging/discharging switching period Psw, and detected voltage Vp:Pb=Vp×Ibamp×sin(2π·t/Psw)where, t is time that has lapsed after the start of the temperature risecontrol.

At step 507, thereafter, the actuator (for example, the boost converter13, inverter 14, motor 11, two-way DC-DC converter 18, or the like) iscontrolled according to the command power Pb. The charging/dischargingpower of the high-voltage battery 12 is thereby controlled so that itagrees with the command power Pb. As a result, charging and dischargingof the high-voltage battery 12 are repeated with the period Psw betweenthe maximum chargeable current Ibmin and the maximum dischargeablecurrent Ibmax and the temperature of the high-voltage battery 12 israised.

According to the sixth embodiment, it is possible to set thecharging/discharging switching period Psw and the amplitude Ibamp in thetemperature rise control, while the maximum chargeable current Ibmin andthe maximum dischargeable current Ibmax are varied according to changein the internal state of the high-voltage battery 12 in the temperaturerise control. Even when the internal state of the high-voltage battery12 changes, the charging/discharging switching period Psw and theamplitude Ibamp in the temperature rise control can be controlled towithin an appropriate range for the temperature rise control. It ispossible to prevent the high-voltage battery 12 from abnormal heatingand promptly raise the temperature of the high-voltage battery 12.

In the sixth embodiment, both the charging/discharging switching periodPsw and the amplitude Ibamp are set according to the maximum chargeablecurrent Ibmin and the maximum dischargeable current Ibmax. Instead, onlyeither the switching period Psw or the amplitude Ibamp may be set.

Seventh Embodiment

In the seventh embodiment, the processing is carried out as describedbelow. When the temperature rise control routine in FIG. 11 is started,the following processing is carried out at steps 601 to 606. At thistime, the same method as at steps 201 to 206 in the temperature risecontrol routine in FIG. 4 described in relation to the second embodimentis used. The differences between the upper and lower limit values(Vbmax, Vbmin) within the voltage use range of the high-voltage battery12 and the sampled present voltage Vp are determined. The allowablevoltage rise and drop (ΔVbmax, ΔVbmin) to the upper and lower limitvalues (Vbmax, Vbmin) within the voltage use range are calculated fromthe differences. Then the maximum chargeable current Ibmin and themaximum dischargeable current Ibmax are set using the allowable voltagerise and drop (ΔVbmax, ΔVbmin), the battery temperature Tp that hasinfluence on the internal resistance, and the upper and lower limitvalues (Ibmax, Ibmin) within the current use range of the high-voltagebattery 12.

At steps 607 to 610, thereafter, the following processing is carried outby the same method as at steps 504 to 507 in the temperature risecontrol routine in FIG. 10 described in relation to the sixthembodiment. The absolute value of the maximum dischargeable currentIbmax and the absolute value of the maximum chargeable current Ibmin areadded to determine charging/discharging amplitude Ibamp. Further thecharging/discharging switching period Psw is calculated from thecharging/discharging amplitude Ibamp and the detected temperature Tp.After the command power Pb is calculated form the charging/dischargingamplitude Ibamp and the charging/discharging switching period Psw, theactuator is controlled according to the command power Pb and thecharging/discharging power of the high-voltage battery 12 is therebycontrolled so that it agrees with the command power Pb.

In the seventh embodiment, the same effect as in the second and sixthembodiments can be provided.

Eighth Embodiment

In the eighth embodiment, the processing is carried out as describedbelow. When the temperature rise control routine in FIG. 12 is started,the following processing is carried out at steps 701 to 707. At thistime, the same method as at steps 201 to 206 in the temperature risecontrol routine in FIG. 6 described in relation to the third embodimentis used. The differences between the upper and lower limit values(Vbmax, Vbmin) within the voltage use range of the high-voltage battery12 and the sampled present voltage Vp are determined. The allowablevoltage rise and drop (ΔVbmax, ΔVbmin) to the upper and lower limitvalues (Vbmax, Vbmin) within the voltage use range are calculated fromthe differences. Then the maximum chargeable current Ibmin and themaximum dischargeable current Ibmax are set based on the allowablevoltage rise and drop (ΔVbmax, ΔVbmin), the internal resistance Rbestimated based on the battery temperature Tp, and the upper and lowerlimit values (Ibmax, Ibmin) within the current use range of thehigh-voltage battery 12.

At steps 708 to 711, thereafter, the following processing is carried outby the same method as at steps 504 to 507 in the temperature risecontrol routine in FIG. 10 described in relation to the sixthembodiment. The charging/discharging amplitude Ibamp and thecharging/discharging switching period Psw are calculated, and thecommand power Pb is calculated from the calculated charging/dischargingamplitude Ibamp and charging/discharging switching period Psw. Theactuator is controlled according to this command power Pb and thecharging/discharging power of the high-voltage battery 12 is therebycontrolled so that the command power Pb is produced.

In the eighth embodiment, the same effect as in the third and sixthembodiments can be obtained.

Ninth Embodiment

In the ninth embodiment, the ECU 20 calculates request torque based onan accelerator position signal from the accelerator position sensor 30,a vehicle speed signal from the vehicle speed sensor 33, and the like.Then the ECU controls the operation of the motor 11 so that this requesttorque is obtained.

Further, the ECU 20 executes the temperature rise control routine inFIG. 13 and thereby carries out the temperature rise control when thetemperature of the high-voltage battery 12 detected by the temperaturesensor 26 is lower than the predetermined temperature. In thetemperature rise control, charging and discharging of the high-voltagebattery 12 are periodically repeated to raise its temperature. It isknown that the Joule heat produced within the high-voltage battery 12during the execution of this the temperature rise control is inproportion to the square of current. Therefore, temperature rise in thehigh-voltage battery 12 can be accelerated by passing larger currentthrough the high-voltage battery 12 regardless of the direction ofcurrent passage (whether charge or discharge).

However, when either charging or discharging is only continuouslycarried out for a long time during the execution of the temperature risecontrol, the polarizing effect of the high-voltage battery 12 isincreased and significant voltage change occurs. As a countermeasuretherefor, it is effective to alternately and periodically repeatcharging and discharging during the execution of the temperature risecontrol. However, the charging/discharging switching period andamplitude for achieving optimum temperature rise vary depending on theinternal state of the high-voltage battery 12 that varies from time totime. Such internal state include not only the remaining capacity SOCand the battery temperature but also the internal resistance, productiontolerance, deterioration, and the like. Therefore, it is preferable tovary the cycle period and amplitude of charging/discharging for bringingout the maximum temperature rise performance according to the internalstate of the high-voltage battery 12. However, the cycle period oramplitude of charging/discharging for achieving optimum temperature risemay be difficult to implement depending on the type of electricalequipment (the two-way DC-DC converter 18, boost converter 13, and motor11 in this embodiment) used for the temperature rise control.

Therefore, it is preferable to carry out the following processing by thetemperature rise control routine in FIG. 13 when the temperature risecontrol is carried out. Based on the charging/discharging cycle periodand amplitude of the high-voltage battery 12, one of electricalequipment most favorable for operating the charging/discharging of thehigh-voltage battery 12 is selected from among multiple pieces ofelectrical equipment.

For example, when the two-way DC-DC converter 18 is selected aselectrical equipment that carries out the temperature rise control, thestep-up operation and step-down operation of the two-way DC-DC converter18 are periodically switched. Charging and discharging are therebyalternately and periodically switched between the high-voltage battery12 and the low-voltage battery 17. When the boost converter 13 isselected as the electrical equipment that carries out the temperaturerise control, the charging and discharging are alternately andperiodically switched between the high-voltage battery 12 and asmoothing capacitor (not shown) of the boost converter 13. When themotor 11 is selected as electrical equipment that carries out thetemperature rise control, the operation mode is alternately andperiodically switched between a motor mode and a generator mode. In themotor mode, the motor 11 is rotationally driven by discharging powerfrom the high-voltage battery 12. In the generator mode, the motor 11 isoperated as a generator and the high-voltage battery 12 is charged.

The temperature rise control routine in FIG. 13 is repeatedly carriedout at predetermined time intervals during the period for which theelectric power to the ECU 20 is on. When this routine is started, first,the temperature (battery temperature) Tp of the high-voltage battery 12detected by the temperature sensor 26 is retrieved at step 2101. At step2102, thereafter, it is checked whether the temperature of thehigh-voltage battery is within the temperature rise control range basedon whether the detected battery temperature Tp is lower than thepredetermined temperature Tth. When the battery temperature Tp is equalto or higher than the predetermined temperature Tth, it is determinedthat the temperature rise control need not be carried out. Then thefollowing processing is not carried out and this routine is terminated.

When it is determined at step 2102 that the battery temperature Tp islower than the predetermined temperature Tth, the processing of step2103 and the following steps in the temperature rise control is carriedout as described below. At step 2103, first, the amplitude Ibamp ofcharging/discharging current corresponding to the present batterytemperature Tp is calculated with reference to map data Map11. The mapdata is used to calculate the amplitude Ibamp of charging/dischargingcurrent using the battery temperature Tp as a parameter. Then a periodPsw corresponding to the present battery temperature Tp and amplitudeIbamp is calculated with reference to map data Map12. This map data isused to calculate the period Psw of charging/discharging current usingthe battery temperature Tp and the amplitude Ibamp as parameters.Ibamp=Map11(Tp)Psw=Map12(Tp,Ibamp)

These maps Map11, Map12 are set beforehand based on experimental data,design data, simulation result, or the like.

At step 2104, thereafter, with reference to the electrical equipmentselection map for the temperature rise control in FIG. 14, one of theelectrical equipment most favorable for operating thecharging/discharging of the high-voltage battery 12 is selected fromamong three pieces of electrical equipment (two-way DC-DC converter 18,boost converter 13, motor 11) used for the temperature rise control.This selection is made based on the amplitude Ibamp ofcharging/discharging current and the charging/discharging switching(cycle) period Psw calculated at step 2103. The electrical equipmentselection map for the temperature rise control in FIG. 14 may be setbeforehand based on experimental data, design data, simulation result,or the like. For example, the map data is so set that, in a range Awhere the amplitude Ibamp and the period Psw are small, the two-wayDC-DC converter 18 is selected. In a range C where the amplitude Ibampand the period Psw are large, the motor 11 is selected. In a range Bbetween these ranges, the boost converter 13 is selected. The processingof step 2104 functions as a selecting means.

At step 2105, subsequently, the command current Ib is calculated by thefollowing expression using the amplitude Ibamp and switching period Pswof charging/discharging current:Ib=Ibamp×sin(2π·t/Psw)where, t is the time that has lapsed after the start of the temperaturerise control.

At step 2106, thereafter, the electrical equipment selected at step 2104is controlled according to the command current Ib calculated at step2105. Charging and discharging of the high-voltage battery 12 arethereby repeated with the period Psw and the amplitude Ibamp and thetemperature of the high-voltage battery 12 is raised.

Instead, the command power Pb may be calculated by the followingexpression using the voltage Vp of the high-voltage battery 12 detectedby the voltage sensor 25 in addition to the amplitude Ibamp andswitching period Psw of charging/discharging current. The electricalequipment selected at step 2104 is controlled according to this commandpower Pb. Charging and discharging of the high-voltage battery 12 arethereby repeated with the period Psw and the current amplitude Ibamp andthe temperature of the high-voltage battery 12 is raised:Pb=Vp×Ibamp×sin(2π·t/Psw)

In the ninth embodiment, the temperature rise control is carried out byselecting one of electrical equipment most favorable for operating thecharging/discharging of the high-voltage battery 12 from among aplurality of electrical equipment based on the cycle period andamplitude of charging/discharging of the high-voltage battery 12.(Examples of such electrical equipment include the two-way DC-DCconverter 18, boost converter 13, and motor 11.) Therefore, it ispossible to select electrical equipment capable of achieving the cycleperiod and amplitude for achieving most favorable temperature rise (or acycle period and an amplitude closest thereto) from among the pluralityof electrical equipment to carry out the temperature rise control. Thusit is possible to enhance the performance of the temperature risecontrol more than with conventional technologies and achieve quicktemperature rise in the high-voltage battery 12.

Tenth Embodiment

When the operation of electrical equipment capable of achieving thecycle period and the amplitude for achieving optimum temperature rise(or a cycle period and an amplitude closest thereto) becomes abnormal,the temperature rise in the high-voltage battery 12 by the temperaturerise control is prevented.

In the tenth embodiment, the temperature rise control routine in FIG. 15is carried out as a countermeasure therefor. That is, the operatingstate (for example, temperature) of at least one (two-way DC-DCconverter 18) of electrical equipment is monitored. When any abnormalityin which its performance is limited or stopped is detected, electricalequipment that operates the charging/discharging of the high-voltagebattery 12 is selected from among the other of electrical equipment tocarry out the temperature rise control.

When the temperature rise control routine in FIG. 15 is started, theprocessing is carried out as described below. At steps 2201 to 2203,first, the following processing is carried out by, the same method as atsteps 2101 to 2103 in the temperature rise control routine in FIG. 13described in relation to the ninth embodiment. When the batterytemperature Tp is lower than the predetermined temperature, it isdetermined that the temperature of the high-voltage battery is withinthe temperature rise control range and the amplitude Ibamp and periodPsw of charging/discharging current of the high-voltage battery 12 arecalculated.

At step 2204, thereafter, the temperature Td of the two-way DC-DCconverter 18 detected by a temperature sensor (not shown) provided inthe two-way DC-DC converter 18 is retrieved. At step 2205, thereafter,the temperature Td of the two-way DC-DC converter 18 is compared with apredetermined abnormality determination temperature Tdth. When it isdetermined that the temperature Td of the two-way DC-DC converter 18 islower than the abnormality determination temperature Tdth, it isdetermined that the two-way DC-DC converter 18 is normally operating. Atstep 2206, then, the selection map for DC-DC converter normal case inFIG. 16A is referred to. Based on the amplitude Ibamp and period Psw ofcharging/discharging current calculated at step 2203, one of electricalequipment most favorable for operating the charging/discharging of thehigh-voltage battery 12 is selected from among three electricalequipment (two-way DC-DC converter 18, boost converter 13, and motor 11)used for the temperature rise control. The selection map for cases wherethe DC-DC converter is normal in FIG. 16A may be identical with theelectrical equipment selection map for the temperature rise control inFIG. 14 used in the ninth embodiment.

Meanwhile, when it is determined at step 2205 that the temperature Td ofthe two-way DC-DC converter 18 is equal to or higher than theabnormality determination temperature Tdth, it is determined that thevoltage conversion operation of the two-way DC-DC converter 18 islimited or stopped. At step 2207, the selection map for DC-DC converterabnormal case in FIG. 16B is referred to. Based on the amplitude Ibampand period Psw of charging/discharging current calculated at step 2203,one of electrical equipment most favorable for operating thecharging/discharging of the high-voltage battery 12 is selected from theremaining two electrical equipment (boost converter 13, motor 11) forthe temperature rise control other than the two-way DC-DC converter 18.In the selection map for DC-DC converter abnormal case in FIG. 16B, therange where the amplitude Ibamp and the period Psw are small is also setas a range B where the boost converter 13 is selected. When the two-wayDC-DC converter 18 is abnormal, therefore, the range B where the boostconverter 13 is selected is expanded to the range A where the two-wayDC-DC converter 18 is selected when the two-way DC-DC converter 18 isnormal. The processing of steps 2204 and 2205 function as an abnormalitydetecting means and the processing of steps 2205 to 2207 functions as aselecting means.

As described above, the selection map data is changed according to thepresence or absence of any abnormality in the two-way DC-DC converter 18and one of electrical equipment most favorable for operating thecharging/discharging of the high-voltage battery 12 is selected. Atsteps 2208 and 2209, thereafter, the following processing is carried outby the same method as at steps 2105 and 2106 in the temperature risecontrol routine in FIG. 13 described in relation to the ninthembodiment. A command current Ib is calculated using the amplitude Ibampand period Psw of charging/discharging current. Thereafter, theelectrical equipment selected at step 2206 or 2207 is controlledaccording to the command current Ib calculated at step 2208. Chargingand discharging of the high-voltage battery 12 are thereby repeated withthe period Psw and the amplitude Ibamp and the temperature of thehigh-voltage battery 12 is raised.

In the tenth embodiment, the operating state (for example, temperature)of the two-way DC-DC converter 18 is monitored. When any abnormality inwhich its performance is limited or stopped is detected, the electricalequipment that operates the charging/discharging of the high-voltagebattery 12 is selected from among the other electrical equipment tocarry out the temperature rise control. Therefore, even when theoperating state of the two-way DC-DC converter 18 becomes abnormal, thetemperature rise control can be carried out by selecting electricalequipment that operates the charging/discharging of the high-voltagebattery 12 from among the other electrical equipment. Thus it ispossible to avoid the prevention of temperature rise in the high-voltagebattery 12 by any abnormality in the two-way DC-DC converter 18.

In the tenth embodiment, abnormality in the two-way DC-DC converter 18is detected. Instead, an abnormality in any other electrical equipment(boost converter 13, motor 11) may be detected or abnormality in two ormore electrical equipment may be detected.

In the tenth embodiment, the temperature of electrical equipment for thetemperature rise control (the temperature Td of the two-way DC-DCconverter 18) is monitored to detect any abnormality. Instead, currentor voltage may be monitored to detect any abnormality or two or moreitems of temperature, current, and voltage may be monitored to detectany abnormality.

In the ninth and tenth embodiments, three electrical equipment are usedas electrical equipment for the temperature rise control. Instead, twoelectrical equipment or four or more electrical equipment may be used.

The electrical equipment for the temperature rise control is not limitedto the two-way DC-DC converter 18, boost converter 13, or motor 11.Instead, for example, an alternator, an electric air conditioner, anelectric power steering device, a DC-DC converter that carries outvoltage conversion only in one way, or the like may be used. In thiscase, the alternator (generator) and another electrical equipment may becombined together to periodically repeat charging and discharging.Alternatively, only either charging or discharging may be periodically(intermittently) repeated with any one of electrical equipment.

Eleventh Embodiment

In the eleventh embodiment, the processing is carried out as describedbelow. When the temperature rise control routine in FIG. 17 is started,first, the temperature Tp of the high-voltage battery 12 detected by thetemperature sensor 26 is retrieved at step 3101. At step 3102,thereafter, it is checked whether the temperature of the high-voltagebattery is within the temperature rise control range based on whetherthe battery temperature Tp is lower than the predetermined temperatureTth. When the battery temperature Tp is equal to or higher than thepredetermined temperature Tth, it is determined that the temperaturerise control need not be carried out. Then the following processing isnot carried out and this routine is terminated.

When it is determined at step 3102 that the battery temperature Tp islower than the predetermined temperature Tth, the processing of step3103 and the following steps in the temperature rise control is carriedout as described below. At step 3103, first, an amplitude basic valueIbamp.bs of charging/discharging current corresponding to the presentbattery temperature Tp is calculated with reference to map data Map13.This map data is used to calculate the amplitude basic value Ibamp.bs ofcharging/discharging current using the battery temperature Tp as aparameter.Ibamp.bs=Map13(Tp)

This amplitude basic value Ibamp.bs is equivalent to amplitude before itis limited by the period Psw of charging/discharging calculated at thenext step, step 3104. The map data Map13 may be set beforehand based onexperimental data, design data, simulation result, or the like. Inaddition to the battery temperature Tp, the current and/or voltage ofthe high-voltage battery 12 may be taken into account to calculate theamplitude basic value Ibamp.bs.

At step 3104, subsequently, the switching period Psw ofcharging/discharging corresponding to the present battery temperature Tpis calculated with reference to map data Map14, which is used tocalculate the period Psw of charging/discharging using the batterytemperature Tp as a parameter.Psw=Map14(Tp)

This map data Map14 may be set beforehand based on experimental data,design data, simulation result, or the like. In addition to the batterytemperature Tp, the current and/or voltage of the high-voltage battery12 may be taken into account to calculate the period Psw.

At step 3105, thereafter, an amplitude limit value Ibamp.max ofcharging/discharging current is calculated based on the period Psw ofcharging/discharging with reference to map data Map15 in FIG. 18. Thisamplitude limit value Ibamp.max is set for the reduction of noise, suchas vibration noise, due to charging/discharging. When the motor 11 isused as the electrical equipment that carries out the temperature risecontrol, the amplitude limit value Ibamp.max is set not only for noisereduction. The amplitude limit value is also set to suppress fluctuationin driving force and fluctuation in number of revolutions due tocharging/discharging for the enhancement of drivability. The map dataMap15 in FIG. 18 may be set beforehand so that the following isimplemented based on experimental data, design data, simulation result,or the like. The amplitude limit value Ibamp.max is reduced in a periodrange (frequency range) where vibration noise and fluctuation in thedriving force of and fluctuation in the number of revolutions of themotor 11 due to charging/discharging are prone to occur.

At step 3106, subsequently, the amplitude basic value Ibamp.bs islimited by the amplitude limit value Ibamp.max (guard processing) todetermine the ultimate amplitude Ibamp of charging/discharging current.Specifically, the amplitude basic value Ibamp.bs and the amplitude limitvalue Ibamp.max are compared with each other and the smaller one istaken as the ultimate amplitude Ibamp of charging/discharging current.Ibamp=Min(Ibamp.bs,Ibamp.max)

The processing of steps 3105 and 3106 functions as a limiting means.

At step 3107, thereafter, the command current Ib is calculated by thefollowing expression using the amplitude Ibamp and period Psw ofcharging/discharging current:Ib=Ibamp×sin(2π·t/Psw)where, t is the time that has lapsed after the start of the temperaturerise control.

At step 3108, thereafter, electrical equipment (for example, the boostconverter 13, inverter 14, motor 11, two-way DC-DC converter 18, or thelike) is controlled according to the command current Ib calculated atstep 3107. Charging and discharging of the high-voltage battery 12 arethereby repeated with the period Psw and the amplitude Ibamp and thetemperature of the high-voltage battery 12 is raised.

Instead, the temperature of the high-voltage battery 12 may be raised bycalculating the command power Pb by the following expression using thevoltage Vp of the high-voltage battery 12 detected by the voltage sensor25, in addition to the amplitude Ibamp and period Psw ofcharging/discharging current. The electrical equipment is controlledaccording to this command power Pb and charging and discharging of thehigh-voltage battery 12 are thereby repeated with the period Psw and thecurrent amplitude Ibamp:Pb=Vp×Ibamp×sin(2π·t/Psw)

In the eleventh embodiment, the amplitude is reduced based on the cycleperiod of charging/discharging of the high-voltage battery 12 so thatvibration noise is reduced during the execution of the temperature risecontrol. Therefore, it is possible to reduce noise, such as vibrationnoise, produced during the execution of the temperature rise control andquickly raise the temperature of the high-voltage battery 12. When themotor 11 is used as the electrical equipment that carries out thetemperature rise control, it is possible to reduce not only noise butalso fluctuation in driving force and quickly raise the temperature ofthe high-voltage battery 12 by limiting the amplitude based on the cycleperiod of charging/discharging.

Twelfth Embodiment

Travel noise such as road noise and wind noise is increased withincrease in vehicle speed. For this reason, noise due to the temperaturerise control which an occupant can hear in low-speed traveling may beobscured by traveling noise in high-speed traveling and the occupant maybe hardly able to hear it. Similarly, it becomes more difficult foroccupants to feel fluctuation in driving force due to the temperaturerise control with increase in vehicle speed.

In the twelfth embodiment, the vehicle speed Spd is also taken intoaccount in addition to the cycle period to calculate the amplitude limitvalue Ibamp.max to limit the amplitude by executing the temperature risecontrol routine in FIG. 19.

When the temperature rise control routine in FIG. 19 is started, first,the battery temperature Tp detected by the temperature sensor 26 and thevehicle speed Spd detected by the vehicle speed sensor 33 are retrievedat step 3201. At steps 3202 to 3204, thereafter, the followingprocessing is carried out by the same method as at steps 3102 to 3104 inthe temperature rise control routine in FIG. 17 described in relation tothe eleventh embodiment. When the battery temperature Tp is lower thanthe predetermined temperature Tth, the amplitude basic value Ibamp.bsand the period Psw corresponding to the battery temperature Tp arecalculated.

At step 3205, thereafter, the amplitude limit value Ibamp.max ofcharging/discharging current is calculated based on the period Psw ofcharging/discharging and the vehicle speed Spd with reference to mapdata Map15 in FIG. 20. At this time, a data map corresponding to thepresent vehicle speed Spd may be selected from among a plurality of mapsset for each vehicle speed Spd to calculate the amplitude limit valueIbamp.max corresponding to the period Psw. Alternatively, the amplitudelimit value Ibamp.max corresponding to the present vehicle speed Spd andperiod Psw may be calculated using one two-dimensional map used tocalculate the amplitude limit value Ibamp.max using the vehicle speedSpd and the period Psw as parameters.

At steps 3206 to 3208, thereafter, the following processing is carriedout by the same method as at steps 3106 to 3108 in the temperature risecontrol routine in FIG. 17 described in relation to the eleventhembodiment. The amplitude basic value Ibamp.bs is limited by theamplitude limit value Ibamp.max (guard processing) to determine theultimate amplitude Ibamp of charging/discharging current. The electricalequipment is controlled according to the command current Ib calculatedusing this amplitude Ibamp and the period Psw. Charging and dischargingof the high-voltage battery 12 are thereby repeated with the period Pswand the amplitude Ibamp and the temperature of the high-voltage battery12 is raised.

According to the twelfth embodiment, in addition to the period ofcharging/discharging, vehicle speed is also taken into account tocalculate the amplitude limit value Ibamp.max and limit the amplitude.Therefore, the limitation of amplitude can be mitigated incorrespondence to the phenomenon that it becomes more difficult for anoccupant to recognize vibration noise or fluctuation in driving forcedue to the temperature rise control with increase in vehicle speed. Itis possible to avoid excessively limiting the amplitude in high-speedtraveling and to minimize degradation in temperature rise performancedue to the limitation of amplitude.

Thirteenth Embodiment

When a driver operates the accelerator pedal 29 to quickly accelerateduring the execution of the temperature rise control, it is preferableto give higher priority to meeting the driver's acceleration requestthan to reducing noise or driving force fluctuation.

In the thirteenth embodiment, by executing the temperature rise controlroutine in FIG. 21, the accelerator pedal depression amount is alsotaken into account in addition to the cycle period to calculate theamplitude limit value Ibamp.max to limit the amplitude.

When the temperature rise control routine in FIG. 21 is started, first,the battery temperature Tp detected by the temperature sensor 26 and theaccelerator pedal depression amount Aacc detected by the acceleratorposition sensor 30 are retrieved at step 3301. At steps 3302 to 3304,thereafter, the following processing is carried out by the same methodas at steps 3102 to 3104 in the temperature rise control routine in FIG.17 described in relation to the eleventh embodiment. When the batterytemperature Tp is lower than the predetermined temperature Tth, theamplitude basic value Ibamp.bs and the period Psw corresponding to thebattery temperature Tp are calculated.

At step 3305, thereafter, the amplitude limit value Ibamp.max ofcharging/discharging current is calculated based on the period Psw ofcharging/discharging and the accelerator pedal depression amount Aaccwith reference to map data Map16 in FIG. 22. At this time, a mapcorresponding to the present accelerator pedal depression amount Aacc isselected from among a plurality of maps set for each accelerator pedaldepression amount Aacc to calculate the amplitude limit value Ibamp.maxcorresponding to the period Psw. Alternatively, the amplitude limitvalue Ibamp.max corresponding to the present accelerator pedaldepression amount Aacc and period Psw may be calculated using onetwo-dimensional map. This two-dimensional map data is used to calculatethe amplitude limit value Ibamp.max using the accelerator pedaldepression amount Aacc and the period Psw as parameters.

At steps 3306 to 3308, thereafter, the following processing is carriedout by the same method as at steps 3106 to 3108 in the temperature risecontrol routine in FIG. 17 described in relation to the eleventhembodiment. The amplitude basic value Ibamp.bs is limited by theamplitude limit value Ibamp.max (guard processing) to determine theultimate amplitude Ibamp of charging/discharging current. The electricalequipment is controlled according to the command current Ib calculatedusing this amplitude Ibamp and the period Psw. Charging and dischargingof the high-voltage battery 12 are thereby repeated with the period Pswand the amplitude Ibamp and the temperature of the high-voltage battery12 is raised.

According to the thirteenth embodiment, in addition to the period ofcharging/discharging, the accelerator pedal depression amount is alsotaken into account to calculate the amplitude limit value Ibamp.max andlimit the amplitude. Therefore, when a driver operates the acceleratorpedal 29 to quickly accelerate during the execution of the temperaturerise control, it is possible to mitigate the limitation of amplitude sothat the driver's acceleration request is met. It is possible to meetthe driver's acceleration request and further accelerate temperaturerise in the high-voltage battery 12 any time during the execution of thetemperature rise control.

Further, when a driver operates the brake pedal 31 to quickly decelerateduring the execution of the temperature rise control, the limitation ofamplitude may be mitigated according to the operation amount of thebrake pedal 31 so that the driver's deceleration request is met. It isessential only that amplitude limiting conditions are varied with thedriver's driving intention taken into account.

In any of the eleventh embodiment to the thirteenth embodiment, theamplitude is limited based on the period of charging/discharging setaccording to the temperature of the high-voltage battery 12 during theexecution of the temperature rise control. Conversely, the period may belimited based on the amplitude of charging/discharging set according tothe temperature, current, voltage, or the like of the high-voltagebattery 12 during the execution of the temperature rise control. Asdescribed above, it is possible to limit the period by limiting theperiod based on the amplitude so that a range where the oscillationamplitude is large does not enter an audible frequency range or alow-frequency range where fluctuation in driving force can be easilyrecognized. Therefore, the same effect can be obtained. Needless to add,both the period and amplitude of charging/discharging may be limited sothat vibration noise and fluctuation in driving force are reduced.

The electrical equipment for the temperature rise control is not limitedto the two-way DC-DC converter 18, boost converter 13, or motor 11.Instead, for example, an alternator, an electric air conditioner, anelectric power steering device, a DC-DC converter that carries outvoltage conversion only in one way, or the like may be used. In thiscase, the alternator (generator) and another electrical equipment may becombined together to periodically repeat charging and discharging. Onlyone of charging and discharging may be periodically (intermittently)repeated with any one of electrical equipment.

Each of the above embodiments is not limited to the temperature risecontrol in the high-voltage battery 12 and may be applied to thetemperature rise control in the low-voltage battery 17.

Each of the above embodiments is not limited to an electric vehicle andmay be applied to and realized in a hybrid electric vehicle using both amotor and an engine as driving sources. Further, each of the aboveembodiments can also be applied to and realized in the temperature risecontrol in a battery mounted in a vehicle using only an engine as adriving source.

What is claimed is:
 1. A battery temperature control system that carriesout temperature rise control to raise temperature of a battery mountedin a vehicle by periodically repeating charging and/or discharging ofthe battery, the battery temperature control system comprising: limitingmeans for limiting at least either of a cycle period or an amplitude ofcharging and/or discharging of the battery so that vibration noiseand/or driving force fluctuation is reduced during execution of thetemperature rise control; and vehicle speed detecting means fordetecting vehicle speed, wherein the limiting means limits at leasteither the cycle period or the amplitude in accordance with the vehiclespeed detected by the vehicle speed detecting means; wherein alimitation value of the at least either the cycle period or theamplitude is mitigated with an increase in the vehicle speed; andwherein the limiting means limits the amplitude based on both the cycleperiod and the vehicle speed.
 2. The battery temperature control systemof claim 1, further comprising: driving intention detecting means fordetecting driver's driving intention, wherein the limiting means limitsat least either the cycle period or the amplitude in accordance with thedriver's driving intention detected by the driving intention detectingmeans.
 3. A battery temperature control system that carries outtemperature rise control to raise temperature of a battery mounted in avehicle by periodically repeating charging or discharging of thebattery, the battery temperature control system comprising: a processingsystem, including a processor, configured to limit at least either acycle period or an amplitude of the charging or discharging of thebattery so that vibration noise or driving force fluctuation is reducedduring execution of the temperature rise control; and a vehicle speeddetector configured to detect a vehicle speed; wherein the processingsystem is configured to limit said at least either the cycle period orthe amplitude in accordance with the vehicle speed detected by thevehicle speed detector; wherein a limitation value of said at leasteither the cycle period or the amplitude is mitigated with an increasein the vehicle speed; and wherein the processing system is configured tolimit the amplitude based on both the cycle period and the vehiclespeed.
 4. The battery temperature control system of claim 3, furthercomprising: a driving intention detector configured to detect a driver'sdriving intention, wherein the processing system is configured to limitsaid at least the cycle period or the amplitude in accordance with thedriver's driving intention detected by the driving intention detector.